The conquerors who spread their seed across Europe in ancient times were prosperous farmers who imported their skills from the Middle East, researchers reported this week.
A study of the Y chromosome - passed down with very little change from father to son - suggests that the men of Europe are descended from populations that moved into Europe 10,000 years ago from the "Fertile Crescent", which stretches from Egypt across the Middle East into present-day Iraq.
"Maybe, back then, it was just sexier to be a farmer," Dr Patricia Balaresque of Britain's University of Leicester said in a statement.
The researchers studied the DNA of 2,574 men from across Europe, they report in the Public Library of Science journal PLoS Biology.
Because the Y chromosome changes so little from one generation to the next, changes can be registered by measuring random genetic mutations. This "molecular clock" painted a picture of genetic spread across Europe from the Middle East, where farming originated.
"We focused on the commonest Y-chromosome lineage in Europe, carried by about 110 million men," Dr Balaresque said.
"It follows a gradient from southeast to northwest, reaching almost 100 per cent frequency in Ireland. We looked at how the lineage is distributed, how diverse it is in different parts of Europe, and how old it is."
More than 80 per cent of European Y chromosomes appear to have the Middle Eastern origin. Separate studies of mitochondrial DNA, passed along almost untouched from mother to daughter, suggest women mostly descend from the hunter-gatherers who dominated southern Europe after the Ice Ages.
A study published in 2003 found that about one in 12 men in Asia carry a version of the Y chromosome that originated in Mongolia nearly 1,000 years ago - and some researchers said it was likely spread by conquering Mongol hordes.
The findings suggest some interesting mixing going on in early Europe and merit more genetic research, Prof. Balaresque said.
"To us, this suggests a reproductive advantage for farming males over indigenous hunter-gatherer males during the switch from hunting and gathering, to farming," she said.